One type of micrometer which is known for measuring the dimensions of a workpiece is a direct reading micrometer having a headstock and a tailstock movably coupled to a bed. Movement of the headstock is detected by a rotary encoder, the encoder output providing an indication of the dimension of the the workpiece. One such type of micrometer is known as the Supermicrometer, Model C, manufactured by the Pratt & Whitney Measuring Systems Operation of West Hartford, CT. When utilized as a direct reading instrument the Model C Micrometer is specified to be accurate to within 0.0001 inches (100 microinches). While this accuracy may be sufficient for some measuring applications, for other applications it is desirable to measure the dimensions of an object to a greater accuracy. However, due to the nature of the rotary encoder which detects the movement of the headstock, direct reading measurements which exceed the 0.0001 inch accuracy are believed to be unattainable with this type of micrometer.
It is therefore one object of the invention to provide a direct reading micrometer of the rotary encoder type which has a measurement accuracy which is greater than an accuracy provided by the rotary encoder.
It is a further object of the invention to provide apparatus and method for modifying a direct reading micrometer of the rotary encoder type to provide a greater measurement accuracy.
It is an other object of the invention to provide a direct reading micrometer having a laser displacement meter for measuring the displacement of the headstock from the tailstock during a measurement operation.
It is a still further object of the invention to provide a direct measurement micrometer system having a laser displacement meter which provides a measurement accuracy of at least 0.000005 inches (5 microinches).